Problem: Simplify the following expression: $t = \dfrac{6z}{4} - \dfrac{-6z}{4}$
Since the expressions have the same denominator we simply combine the numerators: $t = \dfrac{6z - (-6z)}{4}$ Combine like terms: $t = \dfrac{12z}{4}$ Simplify by dividing numerator and denominator by 4: $t = \dfrac{3z}{1}$ $t = 3z$